Prenatal observation of umbilical cord torsion with subsequent premature labor and delivery of a 31-week infant with mild nonimmune hydrops.

Prenatal ultrasonography can recognize torsion of the umbilical cord. Nonimmune hydrops may be associated with torsion. If the vein-to-vein pitch is < 2 cm, torsion may be present. Cardiac failure can occur with umbilical cord torsion and can present as nonimmune hydrops.